The invention relates to an apparatus for cleaning a bath of liquid, in particular a metal-working machine lubricant and/or coolant, by means of a conveyor belt which is fed around a drive roller, driven by a motor, in a chamber of a housing and dips into the bath of liquid.
In particular, coolants are used for cooling and lubricating in the machining of metal. Said coolants have a manufacturer-dependent service life which is, however, impaired by oil leakages, for example from central lubrication systems. As a result of oil floating, the coolant no longer receives oxygen and can no longer breathe. The result is dumping of the coolant, resulting in service life losses, Bacterial cultures are formed which result in skin rashes among the employees and in very unpleasant odor nuisance. This reduces the working hygiene. Furthermore, the waste disposal costs are higher for such a coolant, since the replacement intervals have to be kept very short.
Such apparatuses, also referred to as oil skimmers, are used to keep the necessary lubricant or coolant homogeneous and free of contaminants in machine tools, roll stands or the like. Said lubricant or coolant is fed from a reservoir to a machine and is returned again from the latter to the reservoir enriched with oil, dirt, foam and solids.
A very wide variety of cleaning and filtering apparatuses are used to clean this liquid. A preliminary cleaning can already be brought about in the reservoir itself by sedimentation and flotation. It is true that fairly large and, in particular, specifically heavy particles can be separated out by sedimentation; the sediment is, however, impeded by the flotation, which acts in the opposite direction. In particular, in the case of oil-in-water emulsions, ferritic abrasion often binds to free oil and rises with it.
Also known on the market are conveyor belts of the abovementioned type which dip into the bath of liquid. To remove oil, a counter roller by means of which the conveyor belt is, as it were, squeezed out, is as a rule disposed near the drive roller. The contaminants then flow laterally out of the gap between counter roller and drive roller. Such a cleaning of the conveyor belt leaves very much to be desired since substantial amounts of oil residues, dirt, foam and solids are fed back into the bath again.